The present invention relates, in general, to a compressor for operating a membrane of a diaphragm valve.
A diaphragm valve of a type involved here includes a diaphragm acted upon by a compressor for opening and closing as the diaphragm is pressed against a valve stem of a valve body. The diaphragm may be made, for example, of polymer material. Normally, the compressor is made of metal and is moved by an adjustment drive in such a manner that the diaphragm is deflected by the compressor against the valve stem for closing the diaphragm valve. In open position of the diaphragm valve, the diaphragm is deflected away from the valve stem, as the compressor moves in a direction away from the valve stem. In diaphragm valves of this type, the compressor touches the diaphragm to thereby deflect it. During opening, the compressor executes a partial roll-off motion and is pushed away from the diaphragm.
The polymer diaphragm is a sensitive component of the diaphragm valve and is exposed to increased wear as a result of local overstretching caused by the pressure applied by the compressor and as a result of frictional forces between the compressor and the diaphragm. Friction between the compressor and the diaphragm decreases also the operating force applied by the compressor so that the operation of the diaphragm valve requires an increase in the applied operating force. Wear of the diaphragm and local overstretching thereof reduces the service life of the diaphragm.
It would therefore be desirable and advantageous to provide an improved compressor for operating a membrane of a diaphragm valve to obviate prior art shortcomings and to provide a longer service life of the diaphragm while reducing a friction between the compressor and the diaphragm.